Electron transport layers (ETLs) are crucial for achieving efficient and stable planar perovskite solar cells (PSCs). Reports on versatile inorganic ETLs using a simple film fabrication method and applicability for both low-cost planar regular and inverted PSCs with excellent efficiencies (>22%) and high stability are very limited. Herein, we employ a novel inorganic ZnSe as ETL for both regular and inverted PSCs to improve the efficiency and stability using a simple thermal evaporation method. The TiO₂-ZnSe-FAPbI₃ heterojunction could be formed, resulting in an improved charge collection and a decreased carrier recombination further proved through theoretical calculations. The optimized regular PSCs based on TiO₂/ZnSe have achieved 23.25% efficiency with negligible hysteresis. In addition, the ZnSe ETL can also effectively replace the unstable bathocuproine (BCP) in inverted PSCs. Consequently, the ZnSe-based inverted device realizes a champion efficiency of 22.54%. Moreover, the regular device comprising the TiO₂/ZnSe layers retains 92% of its initial PCE after 10:00 h under 1 Sun continuous illumination and the inverted device comprising the C₆₀/ZnSe layers maintains over 85% of its initial PCE at 85 ℃ for 10:00 h. This highlights one of the best results among universal ETLs in both regular and inverted perovskite photovoltaics.

The improvement in the efficiency of inverted perovskite solar cells (PSCs) is significantly limited by undesirable contact at the NiO_X/perovskite interface. In this study, a novel microstructure-control technology is proposed for fabrication of porous NiO_X films using Pluronic P123 as the structure-directing agent and acetylacetone (AcAc) as the coordination agent. The synthesized porous NiO_X films enhanced the hole extraction efficiency and reduced recombination defects at the NiO_X/perovskite interface. Consequently, without any modification, the power conversion efficiency (PCE) of the PSC with MAPbI₃ as the absorber layer improved from 16.50% to 19.08%. Moreover, the PCE of the device composed of perovskite Cs_0.05(MA_0.15FA_0.85)_0.95Pb(I_0.85Br_0.15)₃ improved from 17.49% to 21.42%. Furthermore, the application of the fabricated porous NiO_X on fluorine-doped tin oxide (FTO) substrates enabled the fabrication of large-area PSCs (1.2 cm²) with a PCE of 19.63%. This study provides a novel strategy for improving the contact at the NiO_X/perovskite interface for the fabrication of high-performance large-area perovskite solar cells.